It could be a bad day for the markets once the yield on the benchmark 10-year Treasury hits 3 percent, closely followed trader Art Cashin told CNBC on Thursday.
"That 3 percent level is both a target and a kind of resistance. Everybody knows it's like touching the third rail," said Cashin, UBS director of floor operations at the New York Stock Exchange. "The assumption is once they do it, all hell will break loose. So we'll wait and see."